VirtualBox is running in Windows 7 as the host. VirtualBox has the two modifications (one is called Guest Additions; don't remember the other). The Virtual machine has "bridged" networking selected. I have SAMBA set up (now, the problem may be here; it has been three or four years since I last did this) on the Linux guest machine. Neither guest nor host sees the other.
From the Windows 7 command prompt, the IP address of the Linux guest pings. The IP address of another computer (a separate Windows 7 on the wireless network) pings from the Linux guest. (I have no idea what IP address the Windows 7 host itself has. The output of "netstat" does not seem to be useful.)
So, it seem to me that something should be working. The only workgroup on the LAN is inventively named WORKGROUP. SMB4K should be seeing something. There must be a simple setup step that I am missing.
(FWIW, there are two processes running smbd, and no process is running nmbd. YaST says that nmbd is set to run. I am not sure what this means.)